When you are introducing your baby to solid food, you don't yet know what he or she will be allergic to. Petit Organics founder Michelle Muller-Marinis shares a way to figure that out: it's called the 4-Day Wait Rule.

Here's how it works. If the first food you want to introduce into your baby's diet is potato, then for four days, you only feed potatoes. If the child is allergic, the reaction would materialize in those four days, maybe through a rash or swelling. If nothing happens, then that food is safe and you can introduce a new one.

Now if the next food on your list is strawberries, you would again need to have a diet of only strawberries for four days. But this time, you can feel free to add the "safe food" you have already tested—in this case, potato. Muller-Marinis explains it in detail in the video, so check that out.